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Factorials everywhere (Posted on 2004-08-16) Difficulty: 3 of 5
The equation a!b!=c! is trivial if we allow a or b to be 0 or 1.

However, adding that 1<a<b<c, also allows trivial solutions: which? What condition should be added to disallow such solutions?

Finally, adding that condition, can you find any solution to the problem?

See The Solution Submitted by Federico Kereki    
Rating: 3.0000 (6 votes)

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Solution Puzzle Solution Comment 7 of 7 |
(Q1) However, adding that 1<a<b<c, also allows trivial solutions: which?
(A1) Trivial solutions like:
(3!)*(5!) =(6!)
(4!)*(23!) =(24!) 
(5!)*(119!) = (120!)
occurs indefinitely.

(Q2) What condition should be added to disallow such solutions?
(A2) The trivial solutions inclusive of (A1) occurs by taking:
{b, c} = {(a-1)!, a!}
so imposing the conditions:
b is NOT equal to (a-1)! and,
c is NOT equal to a!
will certainly disallow the trivial solutions under reference.

(Q3) Finally, adding that condition, can you find any solution to the problem?
(A3) I know of only the solution:
6!*7!=10!



  Posted by K Sengupta on 2022-06-04 23:34:50
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